1. Field of the Invention
This invention relates to a multistage pressure condenser which has a plurality of chambers under different pressures, and which is designed to merge and pressure-feed condensates accumulated in the plurality of chambers.
2. Description of the Related Art
With steam turbine equipment, steam which has finished its work is introduced from a turbine exhaust hood into a condenser, where it is condensed to form condensate. The condensate formed by condensation in the condenser is heated via a feed water heater, and then supplied to a boiler to be formed into steam for use as a drive source for a steam turbine.
When the condensate formed by condensation in the condenser is fed to the feed water heater, the higher the temperature of the condensate, the more advantage is obtained in the aspect of plant efficiency. Thus, a multistage pressure condenser comprising a plurality of chambers at different pressures has so far been used to heat low-pressure-side condensate with steam of a high pressure chamber, thereby imparting a high temperature to the condensate to be supplied to the boiler. Concretely, the low-pressure-side condensate is caused to fall freely as droplets or liquid films in high pressure steam, and heated by convection heating. The use of the multistage pressure condenser can also widen the temperature difference between the temperature of cooling water and the temperature of saturated steam and decrease the area of the heat transfer surface.
With the conventional multistage pressure condenser, low-pressure-side condensate is caused to fall freely as droplets or liquid films in high pressure steam, and heated by convection heating. Thus, the time for which the droplets or liquid films are present in high pressure steam is lengthened to perform efficient heating. To lengthen the time for which the droplets or liquid films of the low-pressure-side condensate are present in high pressure steam, however, there is need to increase the height of falling, thus impeding compactness. If the falling height is minimized for achieving compactness, heating is insufficient, causing disadvantage to the efficiency of the plant.